php 电子围栏算法

最近公司有围栏的需求，要求车辆进入设置好的围栏中时报警，反之亦然。

这个函数解决了判断一个坐标在指定的几个坐标围成的围栏中。
这个围栏可以是任意形状，任意大小，任意区域。不依赖任何第三方。纯函数。

/** * @name 围栏算法，判断一个坐标，是否在围栏里面.如：['113.664673,34.810146','113.681667,34.796896','113.69231,34.794711','113.702009,34.809159'] * @author zlx3323  * @param array $fences 围栏，是一组坐标数组 如：113.674458,34.804719 * @param string $point 要判断的坐标 * @return bool */public function getDistance($macid,$longitude2, $latitude2) {      $userid = DB::name('merchant_shop_commodity')->where('macid',$macid)->value('userid');      $isfence = Gps::name('gps_realtime')->where('macid',$macid)->value('isfence');      $fence = Gps::name('gps_police_setting')->where('userid',$userid)->value('fence');      //判断是否围栏通知      if($fence){          $point = $longitude2.','.$latitude2;          $fences = DB::name('gps_fencelist')->where('macid',$macid)->where('is_round',0)->field('lat_lng,status')->select();          if($fences){              foreach($fences as $k=>$vs){                  $newsfences = json_decode($vs['lat_lng'],true);                  $nvert = count($newsfences[0]);                  $vertx = [];                  $verty = [];                  list($testy, $testx) = explode(',', $point);                  $yes = 0;                  foreach ($newsfences as $r=>$vo) {                      foreach($vo as $k=>$vv){                          list($lng, $lat) = explode(',', $vv);                          $vertx[] = $lng;                          $verty[] = $lat;                      }                      $i = $j = $c = 0;                      for ($i = 0, $j = $nvert - 1; $i < $nvert; $j = $i++) {                          if (( ($verty[$i] > $testy) != ($verty[$j] > $testy) ) &&                              ($testx < ($vertx[$j] - $vertx[$i]) * ($testy - $verty[$i]) / ($verty[$j] - $verty[$i]) + $vertx[$i]))                              $c = !$c;                      }                      unset($verty);                      unset($vertx);                      //判断是否在围栏中                      if($c){                          $yes = 1;                      }                  }                  if($yes ==1){                      return $yes;                  }              }          }      }  }

圆形围栏算法：

//计算圆形围栏距离  public function getroundDistance($macid='',$longitude2='', $latitude2='',$unit=1, $decimal=2){          $userid = DB::name('merchant_shop_commodity')->where('macid',$macid)->value('userid');          $isfence = Gps::name('gps_realtime')->where('macid',$macid)->value('isfence');          $fence = Gps::name('gps_police_setting')->where('userid',$userid)->value('fence');          //判断是否围栏通知          if($fence){              $fences = DB::name('gps_fencelist')->where('macid',$macid)->where('is_round',1)->field('lat_lng,radius,status')->select();              if($fences){                  foreach($fences as $k=>$vo){                    $lat_lng = explode(',', $vo['lat_lng']);                    $fences[$k]['lat'] = $lat_lng[1];                    $fences[$k]['lng'] = $lat_lng[0];                  }                  $yes = 0;                  foreach($fences as $k=>$vo){                      $longitude1 = $vo['lng'];                      $latitude1 = $vo['lat'];                      if($longitude1 && $latitude1){
                          $EARTH_RADIUS = 6370.996; // 地球半径系数                          $PI = 3.1415926;                          $radLat1 = $latitude1 * $PI / 180.0;                          $radLat2 = $latitude2 * $PI / 180.0;                          $radLng1 = $longitude1 * $PI / 180.0;                          $radLng2 = $longitude2 * $PI /180.0;                          $a = $radLat1 - $radLat2;                          $b = $radLng1 - $radLng2;                          $distance = 2 * asin(sqrt(pow(sin($a/2),2) + cos($radLat1) * cos($radLat2) * pow(sin($b/2),2)));                          $distance = $distance * $EARTH_RADIUS * 1000;                          if($unit==2){                            $distance = $distance / 1000;                          }                          $result =  round($distance, $decimal);                          //判断是否在围栏中，radius为半径                          if($result < $vo['radius']){                              $yes = 1;                          }                          if($yes == 1){                              return $yes;                          }                      }                  }              }           }    }

数据库字段示例：